In a typical cellular wireless communications network, communication devices, also known as mobile stations and/or user equipments (UEs), communicate via a Radio Access Network (RAN) to one or more core networks. The radio access network covers a geographical area which is divided into cell areas, with each cell area being served by a base station, e.g., a radio base station (RBS), which in some networks may also be called, for example, a “NodeB” or “eNodeB”. A cell is a geographical area where radio coverage is provided by the radio base station at a base station site or an antenna site in case the antenna and the radio base station are not collocated. Each cell is identified by an identity within the local radio area, which is broadcast in the cell. Another identity identifying the cell uniquely in the whole mobile network is also broadcasted in the cell. One base station may have one or more cells. A cell may be downlink and/or uplink cell. The base stations communicate over the air interface operating on radio frequencies with the user equipments within range of the base stations.
A Universal Mobile Telecommunications System (UMTS) is a third generation (3G) mobile communication system, which evolved from the second generation (2G) Global System for Mobile Communications (GSM). The UMTS terrestrial radio access network (UTRAN) is essentially a RAN using wideband code division multiple access (WCDMA) and/or High Speed Packet Access (HSPA) for user equipments. In a forum known as the Third Generation Partnership Project (3GPP), telecommunications suppliers propose and agree upon standards for third generation networks and UTRAN specifically, and investigate enhanced data rate and radio capacity. In some versions of the RAN as e.g. in UMTS, several base stations may be connected, e.g., by landlines or microwave, to a controller node, such as a radio network controller (RNC) or a base station controller (BSC), which supervises and coordinates various activities of the plural base stations connected thereto. The RNCs are typically connected to one or more core networks.
Specifications for a fourth generation (4G) mobile communication system, i.e. the Evolved Packet System (EPS), have been completed within the 3rd Generation Partnership Project (3GPP) and this work continues in the coming 3GPP releases. The EPS comprises the Evolved Universal Terrestrial Radio Access Network (E-UTRAN), also known as the Long Term Evolution (LTE) radio access, and the Evolved Packet Core (EPC), also known as System Architecture Evolution (SAE) core network. E-UTRAN/LTE is a variant of a 3GPP radio access technology wherein the radio base station nodes are directly connected to the EPC core network rather than to RNCs. In general, in E-UTRAN/LTE the functions of a RNC are distributed between the radio base stations nodes, e.g. eNodeBs in LTE, and the core network. As such, the Radio Access Network (RAN) of an EPS has an essentially “flat” architecture comprising radio base station nodes without reporting to RNCs.
A Wireless Local Area Network (WLAN) is a wireless computer network that links two or more wireless devices using a wireless distribution method within a limited area such as a home, school, computer laboratory, or office building. This gives the wireless devices the ability to move around within a local coverage area and still be connected to the network, and may provide a connection to the wider Internet. Most modern WLANs are based on IEEE 802.11 standards, marketed under the Wi-Fi brand name.
Mobility is a central aspect of many wireless communications networks. The wireless communication network supports mobility of a wireless communication device, i.e. service continuity of the wireless communications device, e.g. by transferring a connection between the wireless communications network and the wireless communications device from one cell to another cell or from one base station or access point to another base station or access point.
Mobility criteria comprise for example when to activate inter-Radio Access Technology (RAT) and inter-frequency measurements and when to hand over the wireless communications device to another base station. Mobility criteria may be set conservatively to ensure good connectivity for all wireless communications devices. This will however lead to unnecessary mobility measures, e.g. inter-RAT/frequency measurements and hand over, for many wireless communications devices. These unnecessary mobility measures will in turn degrade both the performance of the wireless communications network and the performance of the user equipments. The performance of the user equipment will suffer especially if a wireless communications device is unnecessarily handed over to a RAT with lower performance than the current RAT, e.g. handover from a 4G network to a 3G network.